First of all, I would like to apologise in advance as English isn’t my first language. Also, this is my first time posting in the forums so if by making this topic I’m making a faux-pas, as Homer said “it’s my first day”.
I’d propose to add “journey” as a meaning for 旅行. I know I can add personal synonyms, I do it all the time. However, I find it strange not accepting this word for this vocabulary. I double checked it also in jisho.
So, that was my suggestion. I love the work you’ve done creating WaniKani AND maintainting it daily. Keep the good work.